Effects of daily intake of yoghurt enriched with bioactive components on chronic stress responses: A double-blinded randomized controlled trial

Chronic stress has a negative influence on health. The aim was to determine stress reducing effects of yoghurt enriched with bioactive components as compared to normal yoghurt. High-trait anxiety individuals (n = 67) aged 18-63 years participated in a randomized, placebo-controlled, double-blinded intervention with parallel groups. They received either yoghurt enriched with alpha-lactalbumin, casein tripeptides and B vitamins (active) or isoenergetic standard yoghurt (control). To detect changes in psychological and physiological stress, State-Trait Anxiety Inventory, Profile of Mood States, salivary cortisol, inflammatory markers, blood pressure, heart rate variability (HRV) and actigraphy were monitored. We observed higher ratings of vigor (p = 0.047) and reduced feeling of inefficiency (p = 0.048) in the active group. HRV (baseline adjusted mean 49.1 ± 2.3 ms) and recovery index (106.6 ± 33.4) were higher in the active group than in controls (42.5 ± 2.2 ms and 80.0 ± 29.3) (p = 0.046 and p = 0.02, respectively). In conclusion, daily intake of yoghurt enriched with bioactive components may aid in stress coping.